Development of an Environmentally Friendly Adsorbent for the Removal of Toxic Heavy Metals from Aqueous Solution

An effective adsorbent for the removal of heavy metals was manufactured by immobilization of jujube powder. The adsorptions of Cd, Zn and Cu from aqueous solutions by jujube complex beads (Type 1 and Type 2) were studied in a batch adsorption system. The adsorption data were fitted well with the Langmuir isotherm models. The adsorption capacities (β) for Cd, Zn and Cu were 4.23, 2.93 and 3.64 mg/g in Type 1 and 1.24, 0.70 and 1.35 mg/g in Type 2 beads. The removal efficiencies of the Type 2 beads, with a larger unit surface area, were lower than those of the Type 1 due to part of the casein or cyclic AMP being destroyed during the drying process of the Type 1. These values for Type 1 beads were higher than those of all other adsorbents for each heavy metal. A comparison of the kinetic models on the overall adsorption rate showed that the adsorption system was best described by pseudo-first-order kinetics. The removal efficiencies of Cd, Zn and Cu exhibited similar tendencies to those observed in the equilibrium tests. This indicates that the jujube complex beads developed in this study can be used as promising adsorbents for the removal of heavy metals from wastewater.     

Removal of Phosphate from Aqueous Solution by Functionalized Mesoporous Materials

In the present study, the applications of mesoporous materials based on silica, namely post-synthesized, one-pot synthesized, and pure MCM-41, were investigated for the removal of phosphate from aqueous solution. The mesostructures were confirmed by X-ray diffraction, Brunauer?CEmmett?CTeller, Fourier transform spectroscopy, and transmission electron microscopy. The absorptions of phosphate by the mesoporous adsorbents were examined, with different adsorption models used to describe the equilibrium and kinetic data. The maximum adsorption capacities of the mesostructure adsorbents were found to be 45.162, 40.806, and 31.123 mg g^?C1 for the post-synthesized, one-pot synthesized, and pure MCM-41, respectively. The kinetic data showed that the adsorptions of phosphate onto the post-synthesized and pure MCM-41 followed the pseudo-first-order kinetic model, whereas the one-pot synthesized adsorbent was described by the pseudo-second-order model.     

Photocatalytic Degradation of Chlorophenol Compounds using Poly Aromatic Star Copolymer

This study investigated the encapsulation and photocatalysis of chlorophenol compounds in water using porphyrin-(polystyrene-b-2-dimethylaminoethyl acrylate) star polymer. The chloride ions generated during photocatalytic process were identified and quantified. 2,4,6-Trichlorophenol, pentachlorophenol, and 2,4-dichlorophenol were satisfactorily decomposed in the photoreactor using porphyrin-(polystyrene-b-2-dimethylaminoethyl acrylate) star polymer, with removal efficiencies of 2,454, 498, and 760 mg/g of porphyrin-(polystyrene-b-2-dimethylaminoethyl acrylate) star polymer. The half-life times reached around 30 min, with the exception of that for 2,4-dichlorophenol. The star polymer-impregnated porphyrin is a promising photocatalyst for the removal of chlorophenols.     

Removal of Benzene Using the Characteristics of Block Copolymers for Encapsulation

This study assessed the aqueous benzene removal capacity of a polymeric adsorbent, based on an amphiphilic material, in a batch experiment. Two types of polystyrene-block-poly(N-isopropylacrylamide) have structures containing a hydrophobic core and hydrophilic shell. The encapsulation mechanism of benzene by a polymeric adsorbent was investigated, and found to be attributable to the Van der Waals interactions between the benzene aromatic ring and the hydrophobic core of the adsorbent. The equilibrium data were analyzed using the Langmuir and Freundlich adsorption isotherms, and found to be a good fit to both. The maximum adsorption capacity for benzene by the polymeric adsorbent was found to be 194.53 mg/g. The kinetic data followed a pseudo-first-order kinetic model. Polystyrene-block-poly(N-isopropylacrylamide) showed the potential to be an effective adsorbent for application to wastewater treatment.     

Comparison of Surface-Modified Adsorbents for Phosphate Removal in Water

Three novel composite adsorbents, sulfate-coated zeolite (SCZ), hydrotalcite (SCH), and activated alumina (SCAA), were characterized and employed for the removal of phosphate from aqueous solution using equilibrium and kinetic batch experiments. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction spectrum were used to study the surface characteristics of the coated layer. Equilibrium tests showed that the adsorption of phosphate followed both Langmuir and Freundlich isotherms. The powder-type SCZ was better for phosphate removal (maximum binding energy, ???=?111.49?mg?g^?1) compared to hydrotalcite and activated alumina. The adsorption of phosphate was considered to take place mainly by ion exchange. The kinetic data followed a pseudo-second-order kinetic model. The initial adsorption of phosphate onto the sulfate-coated adsorbents was fast, indicating that the sulfate-coated materials developed in this study can be used as promising adsorbents for the removal of phosphate from wastewater or sewage.     

Adsorption of Phosphate by Amino-Functionalized and Co-condensed SBA-15

In this study, the applications of mesoporous materials based on silica, and those with modifications, namely post-synthetic grafting, co-condensation, and pure SBA-15, were investigated for the removal of phosphate from sewage. The mesostructures were confirmed by X-ray diffraction, Brunauer?CEmmett?CTeller, Fourier transform infrared spectroscopy, and transmission electron microscopy. The absorption of phosphate by the mesoporous adsorbents was examined, using different adsorption models to describe the equilibrium and kinetic data. The maximum adsorption capacities of the mesostructured adsorbents were found to be 69.970, 59.890, and 2.018?mg/g for the co-condensation, post-synthetic grafting, and pure SBA-15, respectively. The kinetic data showed that the adsorption of phosphate onto three different mesostructures followed the pseudo-first-order kinetic model.